A report on the status of the Vehicle Emission Test Program, January 1, 1990- December 31, 1990.

"April 1991." -- Cover.

An analysis of the low emission vehicle program in Illinois /

Cover title.

Economic impact of changing the carbon monoxide emission limitations for steel mills, R78-1 /

Includes bibliographical references.

Economic impact of the proposed change in the hydrocarbon emission limitation for petrochemical manufacturing processes (R77-3) /

Project no. 10.065.

Emission reduction banking experience in the United States and its applicability to Illinois /

Project no. 83/7011.

Evaluation of episodic and seasonal emission control for transportation in Illinois /

"December 19, 2001."

Evaluation of episodic and seasonal emission control for transportation in Illinois /

"January 2002."

Potential relaxation of Illinois sulfur dioxide regulations and source-specific emission limits and their effect on the use of Illinois coal /

"October, 1983."

Reanalysis of the effect of proposals to relax vehicle emission standards on Chicago air quality : three reports and a summary.

"April, 1982."

Scope of services for the extension of the Vehicle Emission Test Program /

"November 1990"--Cover.

Uber selektive Emission.

Thesis (doctoral)--Universitat Marburg.

Nagra bidrag till kannedomen om vatskornas emission och reflexion.

Thesis (doctoral)--Upsala.

A compilation of air pollutant emission factors for combustion processes, gasoline evaporation, and selected industrial processes

Bibliography: p. 47-51.

Entanglement induced by spontaneous emission in spatially extended two-atom systems

The role of the collective antisymmetric state in entanglement creation by spontaneous emission in a system of two non-overlapping two-level atoms has been investigated. Populations of the collective atomic states and the Wootters entanglement measure (concurrence) for two sets of initial atomic conditions are calculated and illustrated graphically. Calculations include the dipole-dipole interaction and a spatial separation between the atoms that the antisymmetric state of the system is included throughout even for small interatomic separations. It is shown that spontaneous emission can lead to a transient entanglement between the atoms even if the atoms were prepared initially in an unentangled state. It is found that the ability of spontaneous emission to create transient entanglement relies on the absence of population in the collective symmetric state of the system. For the initial state of only one atom excited, entanglement builds up rapidly in time and reaches a maximum for parameter values corresponding roughly to zero population in the symmetric state. On the other hand, for the initial condition of both atoms excited, the atoms remain unentangled until the symmetric state is depopulated. A simple physical interpretation of these results is given in terms of the diagonal states of the density matrix of the system. We also study entanglement creation in a system of two non-identical atoms of different transition frequencies. It is found that the entanglement between the atoms can be enhanced compared to that for identical atoms, and can decay with two different time scales resulting from the coherent transfer of the population from the symmetric to the antisymmetric state. In addition, it was found that a decaying initial entanglement between the atoms can display a revival behaviour.

Entangled two-photon source using biexciton emission of an asymmetric quantum dot in a cavity

A semiconductor based scheme has been proposed for generating entangled photon pairs from the radiative decay of an electrically pumped biexciton in a quantum dot. Symmetric dots produce polarization entanglement, but experimentally realized asymmetric dots produce photons entangled in both polarization and frequency. In this work, we investigate the possibility of erasing the ���which-path��� information contained in the frequencies of the photons produced by asymmetric quantum dots to recover polarization-entangled photons. We consider a biexciton with nondegenerate intermediate excitonic states in a leaky optical cavity with pairs of degenerate cavity modes close to the nondegenerate exciton transition frequencies. An open quantum system approach is used to compute the polarization entanglement of the two-photon state after it escapes from the cavity, measured by the visibility of two-photon interference fringes. We explicitly relate the two-photon visibility to the degree of the Bell-inequality violation, deriving a threshold at which Bell-inequality violations will be observed. Our results show that an ideal cavity will produce maximally polarization-entangled photon pairs, and even a nonideal cavity will produce partially entangled photon pairs capable of violating a Bell-inequality.